Production of metallic magnesium.



lilo-.778.27m K PATBNTBD 1350.27, 1904. I. L. ROBERTS.

PRODUGTIN 0F METALLIC MAGNBSIUM.

` v APPLIoATIoN FILED n! s1, 1904.

UNiTED STATES y Patented December 27, 1904.

PATENT OFFicE.

JAMES `TURNER MOREHEAD, OF NEW YORK, N. Y.

PRODUCTION OF METALLIC MAGNESIUM. l

SPECIFICATION forming part Of Letters VPatent No. 778,270, dated December 27,1904.'

Application filed May 31, 1904. Serial No. 210,393. l

,in the Production ofiMetallic Magnesium, of

which'the following l'is a specification, reference being had to the drawings accompanying and forming part of the same.

My invention relates to the production of metallic magnesium by electrolysis. Heretofore it has been com-mon to electrolyze a fused bath containing the chlorids of magnesium and other substances; but this method is uneconomical, because 1t is necessary, before preparing the bath, to heatthe magnesium chlorid to drive olf the water carried by it.4 In

this heating a considerable part of the chlorid itself'is volatilized, andso lost. Volatization of the magnesium chlorid also 'continues during electrolysis. I have discovered, however,

thatif the fiuorid of magnesium be added to the bath or electrolyte and the whole electrolyzed metallic magnesium will be obtained with little or no loss of the salts by volatiliza-, tion.

The composition of the electrolyte which I .prefer to use is as follows: one hundred and twenty parts of lithium iuorid, eighty parts of. potassium chlorid, forty parts of sodium chlorid, ten parts of ammonium chlorid, ten parts of magnesium chlorid, eighty par-ts of magnesium fiuorid. and twenty parts of magnesium oxid or carbonate. O

The above mixture becomes liquid at a dullred temperature, and if then it is electrolyzed by direct c urrent metallic magnesium will be yliberated at the cathode and chlorin and oxygen at the anode.

The'composition above described may be varied considerably and good results still be obtained-that is, certain of its constituents may be omitted or others substituted or their proportions varied, so long as magnesium iiuorid and a chlorid of the alkali group are used. For example, the bath may contain simply sodium or potassium chlorid and magnesium fiuorid.- The advantage of using a certain amount Iof the lithium salt resides in sink readily tothe bottom, where it is protected from the air and the electrolytic gases, also for the reason that the lithium salt lowers the fusing-point of the bath. It helps to absorb the oxid or carbonate of magnesium when either is present, butwhether by solution or suspension-I am unable to say. The ammonium and magnesium chloride also lower the specific gravity and fusing-point of the bath; but they are very volatile, and only limited quantities thereof should be used; otherwise considerable waste may result from their being more or less volatilized before the bath is completely fused. Only so much of either should be used as will stand a dullred heat-slightly above the melting tempera- ISAIAH L. ROBERTS, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO' ture of magnesium. The oxid or carbonate 'mentioned is not essential; but if added in such amounts as will be dissolved or suspended in the bath more or less of the oxid or carbonate will be reduced along with the fluorid` and chlorid. It should be observed, however, that 'the oxid and carbonate of magnesium the. substances named assist either as electrov lytes or solvents or by lowering the specific gravity or melting-point of the bath. Hence when only the heavy alkali chloride are used with the magnesium liuorid or,.stated more generally, whenever the liberated metal iioats `on the bath the metal should be protected by a suitable screen from the air and yanode gases.

The specific gravity of the bath should therefore, to obtain`the best results, be regulated to permit the metal to rise readily to the surface or sink readily tothe bottom.

In the accompanying drawings lhave shown convenient apparatus for use in practicing my method. Figure 1 shows in'section an apparatus for all be confined inside the screen.

use with a light bath, wherein the free metal sinks to the bottom; and Fig. 2 shows an apparatus adapted for a heavy bath, in which the metalriss to the surface.

Referring to Fig. 1, Aindicates an iron pot or crucible set in suitable furnace B, heated by a gas-Haine from the burner The pot is covered by a slab of slate D, having an aperture E for the insertion of the carbon anode 'lhe cover is also provided with another opening closed by a lid ll, through which additions to or removals from the hath may be made. A draw-ofiI cock J is provided at the bottom of the pot to permit withdrawal of the metal and other contents when desired. For this purpose the gas-burner is removed and a vessel set under the cock to receive the material.

For heavy baths the apparatus shown in Fig. 2 should be used. This is sul )stantially like the former except for the following: A (.lraw-oif pipe O is provided extending up to the fioating metal, so that the magnesium may be drawn ofll without removing any of the bath. 'lhe cover l) should be securely fastened to the pot, as by bolts, as shown, preferably with an asbestos gasket between the two, to secure an air-tight joint. Depending from the lid is a ring K, projecting' into the bath l'. The magnesium will rise along the sides of the pot and be retained in the annular space outside the ring K, whence it may be withdrawn through the pipe O. A bottom cock J may also be provided, so that the apparatus may also be used for light baths, if desired. The screen K should be made of non-conducting material, as otherwise electrolysis would occur there, and the anode gases would not Porcelain is very effective for this purpose. The anode Gr should iit tightly, as I find that the less air admitted to the pot the better in either case. The air seems to accelerate or assist volatilization more than does an atmosphere of the electrolytic gases. Escape-cocks, as N, may be provided to permit the gases to escape when necessary. It may be noted that a cover for the pot is essential where a heavy bath is used, but may be dispensed with in the other case. In the latter instance, however, it is advantageous, since it tends to prevent volatilization and retains the heat of the bath.

'lhe types ol apparatus described are of course merely e( mvenient forms for practicing my invention, which is a process, and therefore independent of any particular apparatus or mechanism.

1. '.he method of producing metallic magnesium, which consists in electrolyzinga fused bath of magnesium iiuorid containing a chlorid of an alkali, as set forth.

Q. rlhe method of producing metallic magnesium, which consistsin electrolyzinga fused hath containing magnesium fiuorid, a chlorid of an alkali metal, and a lithium salt. as set forth.

3. The method of producing metallic magnesium, which consists in electrolyzing a fused bath containing magnesium fiuorid and two or more alkali-metal chlorids, as set forth.

4. lhe method of producing metallic magnesium, whichconsists in electrolyzinga fused bath containing iluorid and chlorid of magnesium, and one or more chlorids of the alkali-metal group, as set forth.

5. The method of producing metallic magnesium, which consists in eleetrolyzing a fused bath containing magnesium iuorid and another compound of magnesium, and one or more chlorids of the alkali-metal group, as set forth.

6. rllhe method of producing metallic magnesium, which consists in fusing a mixture of magnesium fluorid and chlorids of the alkalimetal groups, and electrolyzing the fused mixture in an atmosphere composed of the gases produced bythe electrolysis, as set forth.

ISAIAH L. ROBERTS. Witnesses:

M. LAwsoN DYER, S. S. DUNHAM. 

